This application generally relates to control of nuclear reactions and more particularly relates to a traveling wave nuclear fission reactor, fuel assembly, and a method of controlling burnup therein.
It is known, in an operating nuclear fission reactor, that neutrons of a known energy are absorbed by nuclides having a high atomic mass. The resulting compound nucleus separates into fission products that include two lower atomic mass fission fragments and also decay products. Nuclides known to undergo such fission by neutrons of all energies include uranium-233, uranium-235 and plutonium-239, which are fissile nuclides. For example, thermal neutrons having a kinetic energy of 0.0253 eV (electron volts) can be used to fission U-235 nuclei. Thorium-232 and uranium-238, which are fertile nuclides, will not undergo induced fission, except with fast neutrons that have a kinetic energy of at least 1 MeV (million electron volts). The total kinetic energy released from each fission event is about 200 MeV. This kinetic energy is eventually transformed into heat.
Moreover, the fission process, which starts with an initial source of neutrons, liberates additional neutrons as well as transforms kinetic energy into heat. This results in a self-sustaining fission chain reaction that is accompanied by continued energy release.
A traveling wave Pyrotron for continuous operation is disclosed in U.S. Pat. No. 3,093,569, issued Jun. 11, 1963 in the names of Richard F. Post, et al. and titled “Traveling Wave Pyrotron.” This patent discloses a continuous operating reactor or device for increasing the energy and density of plasma and conducting nuclear reactions therein. An object of the invention is to provide a Pyrotron where traveling magnetic waves are employed to accomplish trapping, heating and energy recovery of charged particles within individual containment zones, each of which progresses along the machine with time. However, this patent does not appear to disclose a traveling wave nuclear fission reactor, fuel assembly, and a method of controlling burnup therein, as described and claimed herein.
U.S. Pat. No. 3,799,839 issued Mar. 6, 1974 in the names of David L. Fischer, et al. and titled “Reactivity And Power Distribution Control Of Nuclear Reactor” discloses a spatial distribution, amount, density and configuration of burnable poison to control a predetermined amount of excess reactivity and to maintain a constant or stationary power distribution during the operating cycle of a nuclear reactor core. According to this patent, it is an object of the invention to provide an arrangement of burnable poison in a nuclear reactor core which will provide a substantially stationary power distribution in the core throughout the period of the operating cycle. Also, according to this patent, other objects are achieved in accordance with the invention by determining consistent power and concomitant reactivity distributions for the operating cycles: by determining the resulting excess local reactivity, and by providing burnable poison in amount, density and configuration, spatially distributed to substantially match the changes in excess local reactivity throughout the period of the operating cycle. However, this patent does not appear to disclose a traveling wave nuclear fission reactor, fuel assembly, and a method of controlling burnup therein, as described and claimed herein.
U.S. Pat. No. 3,489,646 issued Jan. 13, 1970 in the names of Jean Paul Van Dievoet, et al. and titled “Method of Pulsating or Modulating a Nuclear Reactor” relates to a method of pulsating or modulating the operation of a nuclear reactor. This patent discloses modulating the reactor by periodically varying the neutron flux density. According to this patent, operation of a nuclear reactor is controlled by moving one or more structures containing at least at certain localities, an amount of neutron-active substance, at a place outside the nuclear fission region of the reactor, and thereby modify, in dependence upon the speed of the structure, a neutron flow issuing from the reactor core. The specimens of neutron-active material which thus modify the reactivity of the reactor system from the outside may be neutron-generating and/or neutron-influencing material, such as fissionable material, reflector material or other neutron-influencing substance. However, this patent does not appear to disclose a traveling wave nuclear fission reactor, fuel assembly, and a method of controlling burnup therein, as described and claimed herein.
None of the art recited hereinabove appears to disclose a traveling wave nuclear fission reactor, fuel assembly, and a method of controlling burnup therein, as described and claimed herein.
Therefore, what are needed are a traveling wave nuclear fission reactor, fuel assembly, and a method of controlling burnup therein, as described and claimed herein.